fuse-overlayfs

An implementation of overlay+shiftfs in FUSE for rootless containers.

Usage:

$ fuse-overlayfs -o lowerdir=lowerdir/a:lowerdir/b,upperdir=up,workdir=workdir merged

Specify a different UID/GID mapping:

$ fuse-overlayfs -o uidmapping=0:10:100:100:10000:2000,gidmapping=0:10:100:100:10000:2000,lowerdir=lowerdir/a:lowerdir/b,upperdir=up,workdir=workdir merged

Requirements:

If you are not using the static build as explained in the next chapter, your system needs libfuse > v3.2.1.

• On Fedora: dnf install fuse3-devel
• On Ubuntu > v19.04: apt install libfuse3-dev

Also, please note that, when using fuse-overlayfs from a user namespace (for example, when using rootless podman) a Linux Kernel > v4.18.0 is required.

Static Build (+ Compiling on termux)

This project provides a convenient way to automatically perform a static build using a container. The result is a self-contained binary without dependencies, that can be copied across hosts.

1. Install buildah as explained here;

2. Both the build and deploy host require the special device /dev/fuse; there are a few ways to obtain it:

• install fuse2 or fuse3 using the package manager of your choice (dnf, apt, pacman, etc): the install script will usually create the device automatically; or
• manually create the device with the command mknod /dev/fuse -m 0666 c 10 229 (see this code)

3. Clone this repository, and switch to the top-level folder containing the file "Containerfile.static.ubuntu";

4. Launch the build with the command (note the single dot . at the end):

buildah bud -v $PWD:/build/fuse-overlayfs -t fuse-overlayfs -f ./Containerfile.static.ubuntu .

5. Copy the resulting binary to your host:

sudo cp fuse-overlayfs /usr/bin/

6. Compiling on termux:

Needed: git, make, llvm, clang, libfuse2, libfuse3, build-essential, autoconf, automake, m4

apt install git make llvm clang libfuse2 libfuse3 build-essential autoconf automake m4 

Clone the repo and build:

git clone https://github.com/subhu2008/fuse-overlayfs.git
cd fuse-overlayfs
./autogen.sh
./configure --prefix $PREFIX
make -j$(nproc --all)

Confirm it compiled the fuse-overlayfs binary at dir $PREFIX/bin

fuse-overlayfs --version

Should get the output:

fuse-overlayfs: version 1.17-dev
FUSE library version 3.16.2
using FUSE kernel interface version 7.38
fusermount3 version: 3.16.2